1,2,4-Triazolo-quinazoline-thiones: Non-conventional synthetic approach, study of solvatochromism and antioxidant assessment

A non-conventional methodology has been utilized for the synthesis of a series of 1,2,4-triazolo-quinazolinethiones (2a-1). Here the reaction was carried out between 1,2,4-triazolo-quinazolinones (1a-I), in the presence of 1,4-dioxane. The mixture was irradiated under microwave (100 W) for 7 min to obtain targeted molecules (2a-1). All the synthesized molecules were confirmed by H-1, C-13 NMR and HRMS. The solvatochromic property (absorption spectra) of compounds (2a-1) in solvents of different polarities was studied. The compounds (2a-1) were further subjected for their in vitro free radical screening using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and also screened for their in vitro anti-fungal property against Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger). The results from free radical scavenging assay showed promising activity for compounds 2a, e-i, whereas compound 2d showed significant antioxidant activity when compared to ascorbic acid. In vitro anti fungal study showed that the 1,2,4-triazolo-quinazoline-thiones (2a-I) had significant activity against A. flavus and A. niger compared with widely used antifungal agent Fluconazole. (C) 2016 Elsevier B.V. All rights reserved.